Sand-blasting apparatus



Oct. 7. 1924. 1,511,025

G. w. CHRISTOPH v SAND BLASTING APPARATUS Filed Oct. 27. 192i 2 Sheets-Shag; 1

INVE 012 1 67/ ATTORNEY5.

7 Oct. '7,- 1924- G. w. CHRlSTOPH SAND BLASTING APPARATUS Filed 00%;. 27 1921 2 Sheet-Sheet 2 INVENTOR BY WIN ATTORNEYS.

Patented Oct. 7, 1924.

GEORGE W. CHRISTOIH, OF WAREHOUSE POINT, CONNECTICUT.

SAND-IBLASTING APPARATUS.

Application filed October 27, 1921. Serial No. 510,932.

To all whom it may concern:

Be it known that I, GEORGE WV. GHRis'rorH, citizen of the United States, residing at lVarehouse Point, in the county of Hartford and State of Connecticut, have invented new and useful Improvements in Sand-Blasting Apparatus, of which the following is a specitication.

The present invention relates to sand blasting apparatus and, while capable of general application, it is more particularly useful in connection with sand blasting devices of the generaltype in which relatively small articles are supported within a work chamber and are there subjected to a blast of sand while they are being manipulated by an attendant.

In apparatus of the type above referred to, it is customary to cause the sand, which has been injected into the work chamber and has performed its function upon the work, to be returned into a supply hopper from which it was originally drawn, in order that the same mass of sand may be used over and over again to continue the sand blasting operations, the sand being continuously withdrawn from the .hopper and supplied to a sand blast nozzle within the work chamber and being continuously returned from the work chamber to the hopper as the sand blasting operation progresses.

In the use of such apparatus, fine particles of dust are continually becoming disin tegrated from the grains of sand as the latter pass through the sand blast nozzle and are whirled about within the work chamber. More or less dust and dirt is also produced by the abrasive action of the sand upon the surface of the articles being operated upon. Consequently the proportional amount of dust and dirt which is intermixed with the sand increases gradually during the continued use of the apparatus. as heretofore constructed, and the efiectiveness of the sand as an abrasive element becomes correspondingly diminished, because only clean, sharp sand is effective for the sand blasting operation.

One of the objects of the present invention is to provide improved means for separating dust and dirt from the .sand after it has acted upon the articles within the work chamber so that the sand. when returned to the supply hopper, will be free from dust and may be repeatedly injected into the work chamber without acting any less offectively upon the work.

Another object of the invention is to provide, in connection with a transparent wall section or window in the work chamber of a sand blasting device such as above described, means for keeping said transparent wall section free from dust and dirt, throughout the progress of the sand blasting operation, so that the latter may be clearly and continuously visible from the exterior of the chamber. Sand blasting devices of the general character indicated have heretofore been provided with a ventilating pipe, the pipe opening into the sand blast chamber and being effective to remove a certain amount of dust therefrom.

Another object of this invention is to accomplish the objects already set forth by the use of the usual ventilating pipe.

With these and other objects in View, as may hereinafter appear, the invention consists in the features of construction and combinations and arrangements of parts hereinafter described and particularly pointed out in the appended claims.

The invention will be disclosed with the aid of the accompanying drawings illus trating what is now considered to be the preferred embodiment-thereof.

In the drawings, I

Fig. 1 is a side elevational view of the apparatus; and

2 is a view partially in side elevation and partially in vertical section thereof.

Referring to the. drawings, the invention has been illustrated as embodied in a sand blasting apparatus of a type well. known in the art. In general, this apparatus coma horizontal work support 7,- extendingtransversely across the work chamber; a downwardly directed sand blast nozzle8 located within the work chamber and above the work support; and a feed ipipei9, connee-ting the bottom of the sand hopper 6 with the nozzle 8 for delivering sand to the latter.

In the construction shown, the work chamher 5 is of rectangular cross-sectional shape, having four vertically disposed side walls 10 enclosing the central portion of the chamher, and corresponding inwardly sloping side walls 11 and 12 extending respectively above and below the walls 10. There are four sloping side walls 11, connecting the walls 10 with a rectangular horizontal top wall 13. Two of the sloping side walls 12, as shown in Fig. 2, extend downwardly from the lower edges of the corresponding walls 10 at opposite sides of the apparatus. The two walls 12 just referred to, are con nected at the front and rear of the apparatus by "the two other side walls 12 1) the upper portions which slope inwardly while the lowerport-ions thereof are sul stantially vertical, as indicated at 12. The four side walls 12 do not meet at their lower edges and by reason of the above described vertical portions 12 of the front and rear side walls 12, an elongated opening 35 is provided at the bottom of the work chamber, this opening extending horizontally and leading into a short vertical neck or conduit 14 of horizontally elongated rec-- tangular cross-section, which connects the work chamber 5 with the hopper 6.

The lower portion of the hopper 6 is substantially of the shape of an inverted rectangular pyramid having its: lower e7:- tremity connected through a suitable manually-operated sand valve 15 with the feed pipe 9. The upper portion of the sand hopper 6 comprises two side walls 16 which slope upwardly from opposite side walls of the lower portion of the hopper, and two vertical walls 16 which connect the walls 16. A. filling opening is located in one of the upper walls of the hopper 6 and a suitable closure 17 is provided for said opening. The work chamber 5 and the hopper 6 are rigidly supported by a suitable frame18.

The work support '7 consists of a rectangular tray having a screen-like bottom for supporting the articles to be operated upon, the mesh of the screen being suficiently coarse to permit the free passage therethrough of the sand. The frame of the work support rests upon a pair of horizontal angle iron bars 20, which extend rigidly across the work chamber and are rigidly secured to the walls thereof.

The sand blast nozzle 8 depends from a casting 21 which is supported near the top of the work chamber. The upper end of the feed pipe 9 extends through the sloping side walls at the top of the work charnher and through the side of the casting 21, the feed pipe opening into a chamber 22 within said casting. The sand is drawn through the feed pipe 9 in the usual manner, by means of the injector effect of a current of compressed air which is directed into the chamber 22 through an air conduit 23, entering the work chamber at the top thereof and connected with a suitable compressed air reservoir (not shown).

A partial vacuum is thus created in chamber 22 to cause a current of air to flow into the feed pipe inlet 9 and upward therethrough to carry sand fed in regulated quantities from the sand valve 15 into chamber 22..

At the front of the work chamber the side wall 10 thereof is provided with two hand holes 25 through which an attendant insert his hands to manipulate the articles upon the work rest while they are being subjected to the action of the sand blast. The hand holes 25 are surrounded by annular flanges 26 which are turned inwardly from the work chamber wall and flexible cuffs 27 are fitted over said. flanges. as shown in 2. In accordance with the usual practice, the inner extremities of the cuffs 27 are gathered by means of an elastic cord 27' or the like so that the cuffs will fit tightly around the wrists of the attendant to prevent escape of sand through the hand holes. Suitably hinged doors 26 are arranged at opposite sides of the side walls 10 of the work chamber to permit the insertion and removal of the work supporting; trays, the latter sliding upon the angle iron bars 20. The upper side walls ll of the work chamber are provided with transparent portions 30 constituting windows which render visible the action of the sand blast upon the work.

The construction so far described is Slil elantiall the same as that of a well lu'iou'n type of sand blasting a 'iparatus which luis been in general use heretofore. The ten-- turcs of the present invention have been shown as embodied in the specilir apparatus above described merely by way of illustrative example and it is recognized that the invention is capable of use in onnection with sand blasting devices differing: in man particulars of construction from that described and shown, in the drawings.

alrcail Xplained, the use of such ap paratus esults in the formation of due dirt which becomes intermixed with the sand as it is repeatedly used in the work chamber. The present invention. hov' contemplates the IQIDOYRl of these pa l of dustand dirt from the sand after tl sand has acted upon the work and before it is returned into the hopper 6. In carrying out this feature of the invention. provision is made for gathering together the flying particles of sand and dust and causing them to fall through the lower portion of the work chamber, adjacent the mouth of the neck 14C,

sand and carried away with the air.

To the accomplishment ofthe above result, the work chamber is provided with a false bottom comprising three-plates orpartitions 32, 33 and 33. The plate 32 is spaced at shortdista-nce above the side wall 12 at the side of the exhaust conduit 36. The plates and 33 are arranged with their ends slightly overlapping each other and together these plates form a partitionwhich is spaced a short distance above the opposite side wall 12. The overlapping ends of the partition plates 33 and 33 "are spaced apart to provide an air or ventilating passages?) the function of which will'be hereinafter described. The two plates 32 and 33 termin ate at their lower extremities in straight horizontal edges which are disposed in spaced-apart relation in substantially the same vertical plane, the latter extending axially through the work chamber 5 and thehopper 6. i As the sand reaches the lower portion of the work chamber, the downwardly convergingpartitions 3 and 33 serve as detlectorsto divert the sand toward the vertical plane of the outlet port 35. The velocity ofthe sandis thereby arrested and it is caused to flow in a thin stream over the lower edge of the plate or partition which directs it centrally through the neck 14 and into the hopper 6.

.ln order that a current of air may be forced through thestream otsand and dust issuin from the outlet port 35', the air passage 34, connected, at the rear of the apparati'is. with a ventilating or exhaust conduit 36 leading to a blower or fan 36 by means of which air may be drawn through the passage At the front of the apparatus, the air passage 34- is connected througl'i passage 45, with the interior of the work chamber. Air is admitted to the work chamber through an air inlet in the top wall 13 thereof lVhen the fan connected with the exhaust conduit 36 is operating, air is drawn through'the inlet 39, through the work chamber, the ventilating passage 45 and the air passage into the exhaust cone duit 36, the air passing through the thin stream of sand issuing from the outlet port 35 between the partition plates 32 and33. The lighter particles, such as the dust and dirt, contained in the sand are separated therefrom by the action of the current of air and are drawn into the exhaust conduit 36, and thus only clean sand is permitted to enter the hopper 6. By arranging the lower edges of the plates 32 and 33' at different elevations, bearing the relation shown to chamber,

the mouth of the eXha-ustconduit 36, there is no liability of any of the heavier grains of sand being drawn into the exhaust ,conduit if the force of the air current is prop- .erly regulated. A damper 44 may begpi'ovided by which the force of the currentof air may be regulated atwill for the purpose of rendering its action most efiicientfor the removal of the .dust. Preferably this damper 4.4 is located as shown at the junction of the exhaust-conduit 36 and the air passage 34. It will be noticed alsothat the partition plate 38 overlaps the inner face of the partition plate 83, this arrangement insuring against the escape of sand through the ventilating passage 45. The draft produced in the ventilating passage 45 by the current .of air moving through the passage 34;, effects the elimination from the work chamber of a certain amount of the dust and dirt contained in the sand before the latter reaches the outlet port 85.

In sand blasting devices of this general type heretofore used, difficulty has been eX- perienced by the attendant in watchingthe progress of the blasting operation by reason of the fact that the transparent portions or windows of the work chamber quickly became covered with a layer of dust from sand blasting operation which obscured the vision.

:l n the present construction, the air which drawn in through the inlet 39 is diverted by means of a deflector 40 across the inside surfaces of the windows 30 and serves to keep "these windows free from dust, during the sand blasting operation.

While the particulars of construction herein set forth are well suited to the illustrated embodiment of the invention, these particulars are not. essential since they may be variously modified without departing fromthe true scope ofthe invention as defined by the following claims.

hat is claimed is: I

1. In a sand blasting apparatus, the combination of a workc-hamber in which the sand blasting operation takes place, said chamber having. an outlet at the bottom thereof through which the sand flows by gravity in a thin stream, a work support in said chamber above said outlet, a nozzle for directing a blast of sand against the work in said chamber, an air jacket surrounding thelower walls of the work chamber, said lower walls being provided with an air pa sage connecting said jacket with the work said passage inclining downwardly from said jacket to said chamber to insure against the passage of sand therethrough, a hopper beneath said jacket for receiving the sand after it has operated upon the work, and passed through said outlet and air jacket, and means for drawing air from the work chamber through said passage and causing it to pass through the sand stream in said jacket to effect the removal of dust and dirt from the sand,

2. In a sand blasting apparatus, the combination of. a work chamber in which the sand blasting operation takes place, a work support in said chamber, a nozzle for directing a blast of sand against the work in said chamber, a transparent portion in the wall of said chamber through which the progress of the sand blasting operation may be watched, and means for preventing dust and dirt from accumulating upon the inner face of said transparent portion so as to obscure the view of the interior.

In a sand blasting apparatus, the combination of a work chamber in which the sand blasting operation takes place, a work support in said chamber, a nozzle for directing a blast of sand against the work in said chamber, a transparent portion in the wall of said chamber through which the progress of the sand blasting operation may be watched, and means for directing a draft of air across the inner face of said transparent portion to keep it clear of dust re sulting from the blasting operation.

t. In a sand blasting apparatus, the combination of a work chamber within which the sand blasting operation takes place said chamber having a sand outlet through which the sand may escape after it has acted upon the work, awork support within the work chamber, a nozzle for directing a blast of sand against the work, a hopper for receiving the sand which flows through said outlet, a conduit connecting said hopper with said nozzle, a transparent portion in the wall of the work chamber to render the interior of said chamber visible, and means for producing an air draft and directing it across the inner surface of said transparent portion to keep same'free from dust and dirt during the continuance of the sand blasting operation and for causing the air draft to pass through the sand flowing through said outlet to remove dust and dirt therefrom.

5. In a sand blasting apparatus, the combination, of a work chamber having an air inlet at the top and a horizontally elongated sand outlet at the bottom thereof and side walls sloping upwardly from said outlet at opposite sides of the work chamber, a sand blast nozzle within the work chamber, a work support beneath said nozzle, a hopper beneath the work chamber and connected with said outlet, a conduit connecting said hopper and said nozzle, downwardly sloping partitions spaced from the inner faces of said sloping side. walls, to provide an air jacket between said partitions and chamber walls and to intercept falling particles of sand and deflect them toward the lower edges of said partitions, said lower edges being spaced from each other in, a substantially vertical plane to provide a horizontally elongated outlet port through which the sand may flow in a thin stream across said air jacket, through said sand outlet and into said hopper, and one of said partitions comprising two sections having spaced apart overlapping ends arranged to provide a. passage extending to said air jacket, means for drawing air through said. air passage and air jacket and through said stream of sand to remove dust and dirt from the latter.

6. In a sand blasting apparatus, the cont bination, of a work chamber having an inlet at the top and a horizontally elongated sand outlet at the bottom thereof and side walls sloping upwardly from said outlet at opposite sides of the work chamber, a sand blast nozzle within the work chamber, a work support beneath said nozzle, a hopper beneath the work chamber and connected with said outlet, a conduit connecting said hopper and said nozzle, downwardly sloping partitions spaced from the inner faces of said sloping side walls, to provide an air jacket between said partitions and chamber walls and to intercept falling particles of sand and deflect them toward the lower edges: of said partitions, said lower edges being spaced from each other in a substantially vertical plane to provide a horizontally elongated outlet port through which the sand may flow in a thin stream across said air jacket, through said sand outlet, and into said hopper, and one of said partitions comprising two sections having spaced apart overlapping ends arranged to provide a passage extending to said air jacket, an air exhausting device connected to said air jacket at one side of said work chamber for drawing air through said air passage and air jacket and through said sand stream to remove dust and dirt from the sand, and an extension of the downwardly sloping partition at the side of the work chamber to which the exhausting device is connected for pre venting the production by means of said device of a draft of air through said outlet port.

In testimony whereof I have aiiixed my signature.

GEORGE W. CHRIST-OPE. 

